- Author: Luis Espino
I received several calls and comments about issues with tadpole shrimp this spring. While this pest is well known to growers and PCAs, it can still be difficult to manage during planting time. Mistiming of insecticide application can result in shrimp damage. Tadpole shrimp develop fast, and really fast when it is warm. This spring was warmer than last year during mid to late May, when most of the rice was being flooded and planted. If a field takes long to flood and seed, the shrimp have more time to develop and may injure seedlings as soon as they start germinating in the field. What shrimp size can injure rice? If you can see the shrimp, they can injure rice. However, larger shrimp will cause more injury than smaller shrimp. The figure below shows how, in a field infested with TPS, the stand is reduced more the later the field is seeded after flood (DAF).
Some of the fields where shrimp injury occurred this year are fields where pyrethriods do not control shrimp anymore. In these fields, Dimilin is working well. However, remember that Dimilin may take a few days longer to clear up the shrimp than pyrethroids and copper, especially when the shrimp are large.
When shrimp injury occurs soon after seeding, they will feed on the emerging coleoptile and radicle, completely consuming these tissues. When this happens, seeds won't recover. If only some of the tissue is consumed, seedlings may be able to continue growing once the shrimp is controlled. The picture below shows seedlings where the coleoptile and radicle have been consumed compared to two uninjured seedlings at the bottom of the picture.
If a field is damaged by tadpole shrimp, reseeding is an option. Some trials conducted a couple of years ago by Bruce Linquist showed that the optimum stand is about 25 plants/ft2. Rice plants can compensate when the stand is reduced. For example, when the stand is reduced to 12.5 plants/ft2 (half the optimum), yield is reduced only 10%. In general, reseeding should be considered when the stand is reduced to 10 plants/ft2 or less. Draining the field before reseeding increases the likelihood of establishment of the reseed, but it may not be possible in all cases. When reseeding, use a higher seeding rate to increase the chances of establishment and make sure the shrimp have been controlled. As a grower told me a few years ago, remember that reseeding is a bit of a gamble.
- Author: Kathy Keatley Garvey
Or "B" is for Biodiversity Museum Day.
You, no doubt, saw the stick insects, Madagascar hissing cockroaches and millipedes. And you may have handled them. Scores of children--and many adults--asked to touch or hold them.
The Bohart Museum, directed by Lynn Kimsey, UC Davis distinguished professor of entomology, shared a booth at the Conference Center with the laboratory of Jason Bond, who is the Evert and Marion Schlinger Endowed Chair in Insect Systematics, UC Davis Department of Entomology and Nematology, and associate dean, College of Agricultural and Environmental Sciences. Arthropods from the Bond lab also included a scorpion and a trapdoor spider. The Bohart displayed a number of specimens, including the state insect, the California dogface butterfly, and the Asian giant hornet (nicknamed "murder hornet" by the news media.)
Some 1300 visitors checked out the displays, staffed by scientists from 11 museums or collections on campus:
- Arboretum and Public Garden
- UC Davis Bee Haven
- Bohart Museum of Entomology
- Botanical Conservatory
- California Raptor Center
- Center for Plant Diversity
- Department of Anthropology Museum
- Museum of Wildlife and Fish Biology
- Nematode Collection
- Paleontology Collection
- Phaff Yeast Culture Collection
This was the first year the free, science-based event has been held exposition-style in one facility. A special feature: side trips to several of the museums or collections.
Senior museum scientist Steve Heydon periodically escorted tours from the Conference Center to the Bohart Museum located in Room 1124 of the Academic Surge Building. Currently closed to the public due to COVID-19 pandemic precautions, the Bohart houses a global collection of eight million insect specimens, plus a live "petting zoo" (Madagascar hissing cockroaches, stick insects and tarantulas) and an insect-themed gift shop (now online).
(Editor's Note: More coverage pending)
![Insect enthusiast James Heydon (front) and scientist Ben Maples (back), a UC Davis entomology graduate who works at the California Department of Food and Agriculture, show insects at the Bohart Museum of Entomology on Sunday, March 6 during the 11th annual UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey) Insect enthusiast James Heydon (front) and scientist Ben Maples (back), a UC Davis entomology graduate who works at the California Department of Food and Agriculture, show insects at the Bohart Museum of Entomology on Sunday, March 6 during the 11th annual UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/89405.jpg)
![Hands cradled stick insects in the Bohart Museum of Entomology/Jason Bond lab booth at the UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey) Hands cradled stick insects in the Bohart Museum of Entomology/Jason Bond lab booth at the UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/89406.jpg)
![Ever held a millipede? It was the first time for many visitors at the UC Davis Biodiversity Museum Day. The millipede exhibits were from the Jason Bond lab. (Photo by Kathy Keatley Garvey) Ever held a millipede? It was the first time for many visitors at the UC Davis Biodiversity Museum Day. The millipede exhibits were from the Jason Bond lab. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/89407.jpg)
- Author: Ben Faber
It's not easy to update the IPM Handbook in paperback, but You can check out the latest IPM Pest Management Guidelines for arthropod pests at:
http://ipm.ucanr.edu/PMG/selectnewpest.citrus.html
The other sections will be updated soon. Tune in, and in the meantime if you don't have a copy of the IPM Manual, it's time to get one:
How to order
Obtain Integrated Pest Management for Citrus from the UC ANR catalog, or by mail, by telephone, and at many of the UC County Cooperative Extension offices. For more information, see "How to Order Publications."
Third Edition
Integrated Pest Management for Citrus
Published 2012 · Publication 3303 · 275 pages
How to order List of contents |
Book excerpts: General predators in citrus Fruit disorders in citrus |
High-quality Photographs
More than 500 high-quality color photographs and dozens of drawings and charts will help you identify and manage over 150 different citrus pests and to recognize the important natural enemies of pest insects and mites. The book content includes pest insects, mites, diseases, weeds, nematodes, and vertebrates. Abiotic disorders and crop production and harvest-related problems are also covered.
/h4>/h4>/table>/h4>/h3>/h4>![citrus manual citrus manual](/blogs/blogcore/blogfiles/59886.jpg)
- Author: Luis Espino
I visited a field with leafhopper damage. What was interesting about this field, is that the leafhopper causing the problem was not the aster leafhopper, which is the common one we have in rice. It was a different, green leafhopper that I have seen around in the past, but I have never paid much attention to. I don't even know what its name is (yet). It is green, larger than the aster leafhopper, and moves quite fast. We could not get a picture of it on a rice leaf, so here it is on a weed.
The damage was similar to what I have seen when aster leafhopper feeds on rice. The tip of the leaves get yellow and eventually burned. In this case, the damage was limited to a cold water check, so no treatment is needed.
Another interesting thing is that we found the eggs laid on watergrass plants around the field. Rice did not have any of the oviposition marks. They don't seem to like rice to lay their eggs. That is good because the lesions created due to the egg laying were quite large.
- Author: Luis Espino
Tadpole shrimp (TPS) are starting to pop up in rice fields. A grower asked me when is the period when rice is “safe” from TPS. He is seeing very small shrimp, and seedlings are already past the first leave stage of rice (lsr).
To determine if rice is going to escape TPS injury, two things need to be considered, the rice seedling stage and the size of the TPS. It is difficult to determine the size of TPS, but if you pull one out of the water and its shell is smaller than half the size of a medium grain rice seed, then it won't injure a germinating seed. TPS larger than that will readily feed on germinating seeds and seedlings.
TPS with a shell size about half the size of a rice seed feeding on developing root.
TPS will feed on seedlings until they reach the first leave (when the spike is well developed). TPS don't seem to like feeding on the green tissue. However, they will feed on roots. If the main root is exposed, seedlings are still at risk of TPS injury.
TPS feeding on exposed roots of 1 lsr.
Use this guideline when you scout:
If TPS shell size is... | And the rice stage is... | Risk of injury is... |
Smaller than half the size of a medium grain rice seed |
smaller than 1 lsr | LOW at this point, but may increase as TPS grows |
Smaller than half the size of a medium grain rice seed | 1 lsr or larger | LOW |
Larger than half the size of a medium grain rice seed | smaller than 1 lsr | HIGH |
Larger than half the size of a medium grain rice seed | 1 lsr or larger | LOW, but check the main root. If exposed, it can be consumed by TPS |
One more thing to considering when scouting. If rice escapes injury and TPS are not treated, they will lay eggs that will stay in the soil and hatch next season.
When it comes to TPS management, fields that can be flooded quickly have an advantage over fields that take several days to flood. A quick flood followed by timely seeding will result in seedlings that can reach the 1 lsr before the TPS grow too large. In fields where flooding takes several days, TPS will have a head start and may reach the injuring size before the seedlings reach the 1 lsr.